Critical Synergistic Concentration of Binary Surfactant Mixtures

This paper presents a simple method for determination of synergism in binary surfactant mixtures. A homologous series of cationic alkyltrimethylammonium bromides (CnTAB, with n = 8, 12, 16, 18) mixed with three non-ionic surfactants (n-octanol, methyl isobutyl carbinol, tri(propylene glycol) butyl ether) was chosen as a model system. In addition to the cationic-non-ionic system, the mixture of anionic-non-ionic surfactants (sodium dodecyl sulphate and tri(propylene glycol) butyl ether) was investigated. The foam behavior of one-component solutions and binary mixtures was characterized as a function of surfactant concentration, number of carbons (n) in alkyl chain of CnTAB as well as type of surfactant. It was shown that synergism in foamability could be produced by the ionic-non-ionic systems, and the concentration below the synergism occurs, called the critical synergistic concentration (CSC), that can be easily predicted based on the surface tension data on individual components

Bubble Formation and Motion in Liquids—A Review

In flotation, a bubble acts as a carrier for attached particles. The properties of the gas–liquid interface of the bubble are one of the main factors determining the bubble motion and flotation efficiency. Monitoring of the bubble motion may deliver interesting information about the state of the gas–liquid interface. In the case of pure liquids, a bubble surface is fully mobile, while the presence of surface-active substances (e.g., surfactants) causes diminishing bubble velocity due to the retardation of the interface fluidity. The theoretical prediction of the terminal velocity value for the bubble has been investigated for over a century, delivering a number of various models describing bubble motion in a liquid. This narrative review is devoted to the motion of the bubble in stagnant liquids and is divided into three main sections describing: (i) experimental techniques for tracking bubble motion, (ii) bubble motion and shape deformation in clean water, and (iii) bubble motion in solutions of surface-active substances

Kinetics of froth flotation of naturally hydrophobic solids with different shapes

In this paper, kinetics of flotation of naturally hydrophobic polystyrene platelets with the same roundness, solidity, surface roughness and hydrophobicity but different basic shapes i.e. circular, square and triangular, were studied in pure water and aqueous solutions of non-ionic frother. It was found that the flotation kinetics, and thus bubble attachment, were influenced by the particle shape. The flotation kinetics was the slowest for circular platelets, and then increased with decrease in the surface ratio, defined as the ratio of surface area of circular particle-to-surface area of investigated platelet. The results also showed that at above a certain frother dose, the bubble attachment time and inversed flotation rate constant for all investigated particles increased. The mechanism of this prolongation of time of flotation and bubble attachment to the solid surfaces due to the frother overdosage was presented and discussed. The influence of particle roughness on kinetics of bubble attachment and flotation was analysed and discussed as well